Apparatus for the treatment of hydrocarbon oils



July 18, 1933. E. c. MARSHALLEI' AL APPARATUS FOR THE TREATMENT OF HYDROCARBON OILS Filed May 5, 1928 attorneys.

Patented July 18, 1933 UNITED STATES PATENT. OFFICE EMERY G. MARSHALL, OF KANSAS CITY, MISSOURI, AND MYRON J. BURKHAIRD, OF

KANSAS CITY, KANSAS, ASSIGNORS TO WHITE EAGLE OIL AND REFINING GOM- IPANY, OF KANSAS CITY, MISSOURI APPARATUS FOR THE TREATMENT OF HYDROGARBON OILS Application filed May 3, 1928. Serial No. 274,918.

This invention relates to a process for con verting high boiling point hydrocarbons 1nto low boiling point hydrocarbons, and more particularly the conversion of heavy residual oils of high boiling point obtained from the distillation of ordinary petroleums and heavy petroleums containing few low boiling polnt constituents.

Heretofore considerable difiiculty has been encountered in cracking these heavy residual oils from prior distillations or from natural heavy petroleums containing a minority of low boiling point constituents due to the accumulation of cokey or carbonaceous deposits at various points in the cracking system. These deposits cause frequent shut-downs for the cleaning of the retorts, pipe lines, etc., and in some instances cause serious and dangerous breakage of the apparatus with possible loss of life and property.

It is obvious that if a charging stock consisting of overhead distillate, such as gas oil, solar oil or similar distillate, is utilized, the difficulties encountered will be materially decreased, but owing to the greater expense of such distillates, it is desirable to crack the heavy residual oils and obtain therefrom low boiling point products suitable for use in charging commercial cracking systems, etc.

The object of this invention is to provide a simple, inexpensive and easily controlled,

process for continuously converting heavy hydrocarbon residual oils containing solid or cokey matter in suspension into an overhead distillate free from solid or cokey matter and a solid residue substantially free from liquid and largely free from volatile matter.

For the purpose of cracking heavy petroleums and heavy residual oils to obtain the highest possible return of low boiling point products from the crude run in the refinery, the following process has been devised, which continuously converts such heavy petroleums into a clean overhead distillate having the general nature and characteristics of gas oils, and a residual solid carbon material which does not cause frequent shut-downs of the apparatus.

In the accompanying drawing, a diagrammatic apparatus for carrying out the process is disclosed. In the drawing, 1 is a tubular oil-heater or furnace consisting of a fire box 2, wherein fuel is injected from burner2 to heat the same. In the walls, roof and floors of the fire box 2, are positioned the heating tubes3 for conducting the heavy oils to be heated. The oil heater or furnace is provided with a superimposed gas passage 4 separated from the fire box per se by a suspended arch 5, this gas passage communicating with the fire box through opening 6 and to the atmosphere through stack 7 Within this gas passage 4 are disposed tubes 8 in communication with tubes 3 for conducting the oil to be heated. It will be seen that the series of tubes 8 positioned in gas passage 4 are heated by convection, while the tubes 3 positioned in the fire box 2 are heated by radiation from the burner 2. It is obvious that a considerable portion of heat is absorbed by tubes 3 in fire box 2 by convection as well as radiation.

' The heavy oil to be converted is circulated through the heating tubes in the furnace 1 by means of a pump 9, which receives its immediate supply from feed drum 38 and communicates through pipe 10 with a manifold containing valves 12 and 13. For the purpose of controlling the oil leaving the furnace, there is provided a pipe 14 communicating with the heating tubes through a manifold containing valves 16 and 17. The pipe 14 leads from its manifold to the vaporizing chambers 21 and 22.

The vapors arising from the heavy oil conveyed to the vaporizing chambers pass out through vapor line'23 and enter a conventional fractionating tower 24, where they are separated into a plurality of fractions and each fraction condensed and led through pipe 25, 26 or 27 to suitable storage tanks.

Due to the fact that the heavy oils utilized in this process contain appreciable amounts of water, which would vaporize with serious consequences if introduced into the system, the fresh feed oil from tank 32 is forced by pump 33 into heating drum 34, which is heated by hot oil conducted from the bottom of the fractionator 24 passing through coil 35 positioned in the heating drum 34. The

water content of the feed oil is thus vaporized and escapes from the heating drum through pipe 36, which communicates with fractionator 24. The dried feed oil is passed through pipe 37 to feed drum 38, where it is held until circulated by pump 9 through conduit 10 to the heating furnace.

The vaporizing chambers 21 and 22 are provided with draw-off conduits 29 and 30 leading to the pump 31, the use of which will hereinafter be described in detail.

In the practical working of this process, a heavy fuel oil of, say 18 gravity, is pumped from storage tank 32 by pump 33 to the heating drum 34, where the moisture content is driven off, the oil then passing to feed drum 38 and drawn therefrom by pump 9 and forced through pipe 10, valve 12 to the convection tube bank 8 of the furnace, the valve 13 being closed. From the convection bank 8 the oil passes to the radiant tube bank 3 and flows from the furnace through valve 17 into pipe line 14, the valve 16 being closed. Pipe line 14 conveys the heated oil to either of the vaporizing chambers 21 or 22 through either valve 19 and 20, depending on which chamher is being utilized.

The conditions of temperature and pressure which are maintained in the various parts of the system will vary to some extent depending upon such factors as size of apparatus, character of the charge oil, proportion of overhead products desired, dryness of coke desired, and the like. By way of example, it may be stated that satisfactory operation can be secured by charging a fuel oil of the character above stated and heating the oil in the heating tubes 3 and 8 to an exit temperature of from 850 to 900 F. under an exit pressure; i. e., the pressure in line 14 just prior to pressure release from valve 19 or valve 20, of about 500 pounds per square inch, the pressure in vaporizer 21 or vaporizer 22 being only so much above atmospheric as is required to overcome the flow resistance through the following parts of the system, say 15 to 30 pounds per square inch. With these conditions of operation and with a charge oil of the character specified, the products of vaporization will ordinarily be approximately 5% to 10% of gasoline-like hydrocarbons calculated on the total weight of the charge, 50% to of products of the general nature of gas oil having a boiling range of approximately 600 to 700 F., and the remainder a substantially dry solid carbonaceous or coke residue.

At the beginning of a run and before the system has been heated sufliciently to effect complete separation into vapor and solid matter, there will remain in the particular vaporizing chamber being used a liquid residum which is drawn 01f through valve 29 or 30 and conveyed by pump 31 to be reintroduced into the feed line 10. When suflicient heat the vaporizing drums 21 and 22 is initiated.

That is, solid carbon is deposited in the vaporizing chamber, and the vapors generated pass off through pipe line 23 to the fractionating tower 24.

When the particular vaporizing chamber used is clogged or filled by the coke deposit, the incoming heated oil is conveyed to the clean vaporizing chamber by suitable valves 19 and 20. The deposit of coke is then cleaned out of the choked chamber and it is placed in condition for further use.

It will be noted that the heaviest overhead stock removed in the fractionating tower flows downwardly through pipe 28 and passes through coil 35 to furnish heat for dehydrating the oil in drum 34. This oil may be removed from the system to a storage tank through pipe line 40, or it may be run into storage drum 38 and re-run through the furnace.

Some types of heavy residual oils require a very vigorous heat treatment to break them up into an overhead vapor and a residual solid carbon, and means for treating such oils is provided in this process. When it is desired to increase the severity of treatment, the order of flow within the furnace is reversed by means of the entry and exit valve systems. For instance, in the example previously given, the oil being circulated through pipe 10 was diverted by valves 11 and 12 so that the oil first passed into the convection pipe bank and subsequently through the radiant pipe bank, leaving the furnace through valves 17 and 15-, the oil then being run into pipe line 14. To increase the severity of treatment, the oil flow from pipe 10 is allowed to flow through valve 13, valve 12 being closed. This causes the oil to enter the radiant pipe bank first, where its temperature is raised to a high degree before it passes through the convection pipe bank. During its egress from the furnace, the valve 17 is closed and the flow is through valves 16 and 15 into pipe line 14.

As the continuous operation of the furnace is vital to the economy of the process, it becomes necessary to reduce to a minimum the deposition of coke in the heating banks. Coke is deposited in two ways, first, by the settling of the coke formed due to too slow a speed of the feed stream, and secondly, by the. vaporizing of the feed stream removing such a large quantity of the carrier fluid that the coke drops from suspension. To avoid these difliculties a considerable velocity of the fuel stream is maintained, this speed being controlledby maintaining a back pressure upon the stream suflicient to preas a heavy magma carrying the coke in suspension formed from the vaporization of the normal charge of fuel oil which has passed through the .heater. those skilled in the art that this unit, in addition to its use for reducing fuel oils, might also he used for the primary distillation of It will be obvious to crude oil should it become necessary, and it is therefore a unit of great flexibility and utility for various petroleum refining uses.

We claim: v

An apparatus for cracking petroleum residue comprising a heating unit, a pipe through which the oil passes having a portion subject to radiant heat from the unit and a portion subject to heat by convection from the unit, a pair of parallel manifolds connected to each of said portions, an oil supply means in communication with one of the said manifolds, an outlet pipe in communication with the other of said manifolds, vaporizing means to which the outlet pipe leads, and

means enabling the oil to be initially heated either by radiation or convection.

'EMERY c; MARSHALL. 'MYRON J. BURKHABD. 

